As early as 1305...

An inventory from 1305 lists about 20 pieces.

In the 17th century, the collection presented "over 60 kinds of precious relics and five or six beautiful shrines", all locked in the treasury of the collegiate church, guarded by a canoness: 'la coustre'. Only the shrine to the body of St Waudru remained surmounted at all times on the high altar.

The chapter that succeeded the cloistered community benefited from donations from the counts of Hainaut, who became the secular clergymen and lawyers of this institution. In 1250, Margaret of Constantinople donated a splendid case for the head of St Waudru. While we know that Philippe le Bon left a relic in the treasury at the time of the assizes of the Toison d'Or in Mons in 1451, we do not know what donations might have been made by Marie and Maximilian of Austria, Philippe le Beau, Joanna of Aragon or the future Charles V: however, some of them offered their effigy for the stained-glass windows overlooking the apse.

It goes without saying that the canonesses increased the precious heritage of their beloved church, either in their lifetime or in their will.

These treasures accumulated at the collegiate church over the centuries were taken in 1793 during the first French occupation. Only the relics of St Waudru and altar furniture were saved, as well as the objects that have reached us. In 1797, a public sale dispersed everything else that remained of the furniture, turning the church into a disused place. After the occupation, the objects of worship and reliquaries were restored. The current inventory – which nonetheless remains one of the richest treasures in Wallonia – seems unremarkable compared with the older lists, which included great carved shrines from the Middle Ages to the 17th century.

After previously being kept in the treasury (the current sacristy) and then in a glass case situated behind the high altar, since 1958 the treasure has been displayed in the former chapter house.